Obesity affects an ever-increasing proportion of the population of Western cultures. Nearly one-third of adults in the United States are in excess of their ideal body weight by at least 20%. Obesity has become a major public health problem, at least in part because it is associated with other health problems such as hypertension, elevated blood lipids, coronary artery disease, osteoarthritis and Type II or non-insulin-dependent diabetes mellitus (NIDDM). In the United States alone, there are an estimated 6-10 million individuals with NIDDM, including 18% of the population over 65 years of age and most of these individuals are obese (Harris et al. Diabetes 36:523-534, 1987).
According to conventional wisdom, stability in body composition requires that energy intake equals expenditure, at least over a prolonged period of time. Such wisdom therefore requires that obese persons reduce their food intake in order to reduce their weight and their percent body fat. However, while reduction of caloric intake can lead to short-term weight loss, the lost weight is often regained. Moreover, some evidence indicates that prolonged fluctuation of body weight can lead to weight increases and to increased body fat content.
It appears that there may be a signaling system that adjusts appetite, and accordingly food intake, to preserve a constant total adipose tissue mass. The nature of this signaling system has been examined in a variety of animal experiments involving induced weight change (Cohn et al., Yale J. Biol. Med. 34:598-607, 1962; Harris et al., Proc. Soc. Exp. Biol. Med. 191:82-89, 1989; and Wilson et al., Am. J. Physiol. 259: R1148-R1155, 1990); lipectomy (Forger et al., Metabolism 37:782-86, 1988; Liebelt et al., Ann. N.Y. Acad. Sci. 131:559-82, 1965; and Chlouverakis et al., Metabolism 23:133-37, 1974); plasma transfer from obese or satiated animals to hungry animals (Davis et al., Science 156:1247-48, 1967; Davis et al., J. Comp. Physiol. Psychol. 67:407-14, 1969; and King, Physiol. Psychol. 4:405-08, 1976); and parabiosis between obese and lean animals (Hervey, J. Physiol. 145:336-52, 1959; Parameswaran et al., Am. J. Physiol. 232:R150-R157, 1977; Nishizawa et al., Am. J. Physiol. 239:R344-351, 1980; Harris et al., Am. J. Physiol. 257: R326-R336, 1989; Schmidt et al., Acta Physiol. Acad. Sci. Hung. Tomus 36:293-98, 1969; Coleman et al., Diabetologia 9:294-98, 1973; Harris et al., Int. J. Obesity 11:275-83, 1987; and Coleman et al., Am. J. Physiol. 217:1298-1304, 1969).
Such studies may have identified certain factors that are involved in regulating obesity and body fat content, but confusion exists as to how to use such information to treat obesity. For example, Fried et al., 130 J. Nutr. 3127S-3131S (2000) has disclosed that serum leptin levels are usually elevated in obesity, indicating that lower serum levels of leptin may be beneficial for treating obesity. However, earlier animal data indicated that a leptin deficiency might lead to obesity. Mice that have homozygous mutant ob genes (ob/ob) have been reported to be obese but when given daily injections of recombinant leptin, their food intake was markedly inhibited and they experienced a reduction in body weight and fat. It is known that leptin is a protein expressed by the ob gene and that it is secreted by adipose tissue. Some researches have provided data indicating that leptin is a satiety factor and a regulator of metabolism (Levin et al., 1996 Proc. Natl Acad. Sci. USA 93:1726-1730). Hence, the relationship between leptin levels and body fat has been contradictory. See also, Pelleymounter et al., 1995, Science 269:540-543; Halaas et al., 1995 Science 269: 543-546; and Campfield et al., 1995 Science 269:546-549.
A number of studies have been conducted on the role of dietary fiber in health and disease. Some studies comparing the effects of various fiber sources on cholesterol have concluded that soluble cellulose-like materials reduce cholesterol levels. For example, U.S. Pat. Nos. 5,585,366 and 5,721,221 to Gallaher et al. disclose methods for reducing cholesterol levels in mammalian blood by administering high viscosity water-soluble cellulose derivatives such as hydroxypropyl methylcellulose. U.S. Pat. No. 6,020,324 to Jamas et al. discloses dietary supplements containing intact whole β-glucan in an amount sufficient to lower serum cholesterol levels. However, these patents do not provide treatments for reducing body fat.
Current weight loss treatment regimens generally either have negative side effects or are not particularly effective. Accordingly, a new approach is needed to regulating body fat content.